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Backgrounder on License for Depleted Uranium at U.S. Army Sites

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The Nuclear Regulatory Commission is reviewing an application from the U.S. Army to possess and manage depleted uranium (DU) at training sites across the country. Filed in June 2015, the request would add 15 sites to a license the NRC issued in October 2013 for two sites in Hawaii. The Army wants to apply the same programs for environmental monitoring, radiation safety and physical security to all 17 sites.

The proposed physical security and radiation safety programs are similar to ones in the existing license. But the proposed strategy for routine environmental monitoring differs from what is in the license. The new program would address exposure from ground disturbing activities. It contains criteria for developing separate environmental monitoring plans for each of the 17 sites. If the NRC accepts the new program, schedules to develop and implement plans for each site would become requirements in the amended license. They would then be subject to NRC inspection and enforcement.

The license is needed for DU from spotting rounds that were part of the 1960s-era Davy Crockett weapon system. Used for targeting accuracy, the spotting rounds emitted white smoke on impact but did not explode. Remnants of the tail assemblies remain at sites where the Army trained on the weapons system. This system was previously classified and records of its use were closely guarded.


Natural uranium is made up of three isotopes: U-234, U-235 and U-238. "Depleted" uranium has a lower percentage of U-234 and U-235 than natural uranium and is less radioactive. DU is about twice as dense as lead, making it useful in commercial and military applications. It can be toxic to the kidneys if ingested in large amounts, such as by inhaling dust or drinking contaminated water.

A number of Army sites have DU fragments from spotting rounds left from training with the Davy Crockett system from 1960-1968. The Atomic Energy Commission, the NRC's predecessor, gave the Army a license to make and distribute the spotting rounds. Under that license, the Army distributed the rounds for training. Each round contained about six ounces of DU. That license expired in 1978, after the Army had stopped producing and distributing the spotting rounds.

In 2005, the Army found tail assemblies from the spotting rounds at the Schofield Barracks on Oahu. That discovery prompted a review of all sites that trained with the system. The Army found DU at other sites, including the Pohakuloa Training Area on the big island of Hawaii.  Under NRC regulations, the Army must have a license to possess this material. It applied in November 2008. The NRC approved a license for the two Hawaiian sites in 2013.

An Army information booklet states that the DU is mostly in large fragments. It is on operational ranges not accessible to the public. Data the Army collected and analyzed show there is no immediate health risk to people who work at the ranges, live nearby or travel near the sites. The high density and large fragment size mean the DU cannot easily become airborne or move off-site.

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The NRC's role

M101 Spotting Round (Source: U.S. Army)[2].
M101 Spotting Round (Source: U.S. Army).

Part of the NRC's role is to oversee licensed "source material," which includes DU. The NRC license allows the Army to possess up to 275 pounds of DU at the two Hawaiian sites. It requires the Army to comply with NRC regulations and standards for protecting the public and the environment from radiation and is subject to NRC inspections and periodic reviews. Those requirements will extend to the 15 other sites if the NRC approves a revised license. The license amendment will also update the amount of depleted uranium that the Army may possess.

The license requires the Army to have environmental monitoring as well as radiation safety and physical security plans. These requirements are meant to ensure the DU will not pose a future health risk. The license does not authorize the Army to use the DU or decommission the sites. Any cleanup would require additional review and approval by the NRC to ensure that public health and safety will continue to be protected.

The amended license will ensure the Army has carefully studied the additional sites and developed site-specific environmental radiation monitoring plans. The additional sites include Forts Benning and Gordon (Georgia); Forts Campbell and Knox (Kentucky); Fort Carson (Colorado); Fort Hood (Texas); Joint Base Lewis-McChord/Yakima Training Center (Washington); Fort Bragg (North Carolina); Fort Polk (Louisiana); Fort Sill (Oklahoma); Fort Jackson (South Carolina); Fort Hunter Liggett (California); Fort Greeley (Alaska); Joint Base McGuire-Dix-Lakehurst (New Jersey); and Fort Riley (Kansas).

For additional information, see the Army's website on depleted uranium in Hawaii.

November 2015

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Page Last Reviewed/Updated Monday, November 16, 2015